Direct energy transfer from a drive fluid to a primary fluid to be transported is described in the prior art.
Thus, U.S. Pat. No. 3,046,732, and U.S. Pat. No. 4,485,518 describe devices and methods wherein momentum and energy are transferred from a first fluid to a second fluid.
The teaching contained in this U.S. Pat. No. 3,046,732 has the principal goal of minimizing shear effects created in the primary fluid to be pumped that may appear at the interfaces between the fluid and the mechanical parts of the device. For this purpose, the invention consists of separating the drive fluid into two parts, ejecting a first part of this fluid through orifices located on a rotor into a primary fluid, and using the fluid jet resulting from the second part of the drive fluid passing through a central orifice to drive the first part of the drive fluid and the primary fluid. Thus, the shear that might appear between a fluid and a mechanical part is minimized. The drive fluid jets are emitted continuously through ejection orifices.
The problems generated by contact between particles and mechanical parts of the device may lead to decreased reliability of the device and more frequent servicing to replace parts.
U.S. Pat. No. 4,485,518 teaches ejecting a drive fluid in the form of jets through orifices and grooves located on the outside wall of a rotating part, said part being positioned inside a pipe in which a primary fluid to be pumped circulates. The drive fluid jets emerging when this part rotates transfer their energy tangentially to the primary fluid, and it is this tangentiality that may cause an imbalance in energy transfer.
The use of devices utilizing the energy supplied by jets for propulsion in the shipbuilding or aerospace industries is also known.
Jet energy is also utilized in classical jet pumps described for example in Patent FR-2,617,245 by the applicant. Such devices emit a continuous high-speed axial jet which, by shear at the periphery, entrains the fluid to be transported and leads to lowered efficiency in energy utilization. Moreover, such pumps can present problems such as lowered intake pressure causing substantial degassing, cavitation phenomena, and wear at the nozzles due to the high fluid speeds and the possible presence of solid particles in the fluids with which they are in contact. These drawbacks impair the efficiency of these devices. Moreover, the regulation of such pumps to operate optimally requires knowledge of the values of parameters that are often variable and difficult to measure.
Thus, existing devices do not allow simultaneous generation of a variable-frequency variable-length intermittent axial jet and an axial or annular rotating layer of fluid, said jets having an effect identical to the effect obtained by the mechanical type of piston normally used while avoiding the drawbacks associated with the latter, particularly problems when mechanical parts rotate with respect to each other and wear out.